In many situations, bundles of parallel pipes are installed and it is necessary or desirable to keep the pipes from contacting each other. In one typical installation, one or more pipes are installed inside an underground or underwater conduit and the pipes must be separated from each other to prevent galvanic corrosion. In the past, such separation has been achieved by means of spacers on the pipes which hold the pipes apart. Such spacers have either been made in two pieces which are clamped together around the pipe, or in a single piece which is slipped over the end of the pipe and then moved down the pipe to the place where the separation is required. These one piece spacers are usually made of rubber or other elastomeric material which has a relatively high coefficient of friction with the pipe. In some cases, it is necessary to pull a pipe on which such spacers are mounted thousands of feet through a casing to the final installation so it is important to be sure that all of the spacers stay in place to maintain the separation between the pipes. The high coefficient of friction between the spacer and the pipe works to hold the spacer in place on the pipe, but also works to apply a longitudinal force due to frictional force exerted by its engagement with the casing. Because of this, when the pipe is pulled through the casing it is not possible to know whether the spacers have stayed in place.